Methylthymol Blue Research Articles

Equilibria of aluminium (III) complexes with methylthymol blue

A potentiometric and spectrophotometric study of aluminium (III) complexes with methylthymol blue has been performed in aqueous solutions. Evidence was found for the formation of 1:1 and 2:1 (metal: dye) complexes and it was concluded that protonated and hydroxo complexes of both 1:1 and 2:1 complexes were formed in addition to the neutral complexes. The formation constants were determined and possible structures for the complexes were discussed.

Flow injection and photometric determination of sulfate in rainwater with methylthymol blue

The automated methylthymol blue method for determination of sulfate has been adapted to flow injection sample processing. Prominent features of the method include a linear calibration curve up to 6 mg/L, approximate sensitivity of 0.1 mg/L, and sampling rate of 20 per hour. Average precision was 4.1% and average accuracy evaluated by comparison of results with those obtained by ion chromatography was 97%.

Formation of mixed complexes of thorium(IV) with some multidentate ligands

The formation of mixed complexes, ThAH 2 B (with nitrilotriacetic acid, H 3 A and thoron, H 5 B), ThAHB, ThAB (with H 3 A and methyl thymol blue, H 6 B), is described. The corresponding equilibrium constants have been determined from pH-metric measurements at 25° and at an ionic strength of 0.50 M(NaNO 3 ). A detailed analysis of the experimental data show that the mixed complexes of methyl thymol blue are more stable than ThAH 2 B, which breaks into simple species, ThBH, ThB, ThB(OH), etc., above pH ∼ 5.5.

Flow injection determinations of polyphosphates based on colored metal complexes of xylenol orange and methylthymol blue

Substitution reactions between samples and colored metal complexes, such as magnesium-methylthymol blue and cerium(III)-xylenol orange, are applied to flow injection determinations of orthophosphate, diphosphate, triphosphate and EDTA. Various types of manifold with a stopped-flow device are used; the importance of addition of reagents in a logical sequence is stressed. Kinetic and thermodynamic factors associated with the substitution reactions were found to be significantly reflected in the f.i.a. profiles and stopped-flow signals. The working ranges of the methods are 10 -5–10 -4 M.

Protonated, hydroxo and mixed protonated-hydroxo complex equilibria of the rare earth ions with methyl thymol blue

Complexation reactions of the rare earth ions, Y(III), La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), Tb(III), Dy(III), Ho(III), Er(III), Tm(III), Yb(III) and Lu(III) with 3,3′-bis[N,N′di(carboxymethyl)-aminomethyl]-thymolsulphonphthalein[methyl thymol blue, abbr. mtb] have been investigated potentiometrically at 30°C. Equilibria studied (at μ = 0.10) under three different situations, (i) considering the presence of metal hydroxo complex, (ii) ignoring the existence of M(OH) species and (iii) assuming 100% metal mtb association, indicate that the equilibrium constants obtained under these situations are highly close.

Spectrophotometric determination of zinc(II) and cadmiun(II) with methylthymol blue, oxine derivatives and cetylpyridinium chloride

Zinc(II) or cadmium(II) rapidly forms a mixed complex with methylthymol blue(MTB), cetylpyridinium chloride(CPC) and 5-nitroso-8-quinolinol (NO-oxine) {for zinc(II)} or 2-methyl-8-oxine (CH3-oxine) {for cadmium(II)} in a weak basic medium. The absorbance of the cadmium(II) complex at 630 nm (λmax) and that of the zinc(II) complex at 620 nm (λmax) were constant over the pH range from 7.6 to 9.0 for 3 h. The molar ratio of metal, MTB, oxine derivative and CPC in the mixed complex was a 1:1:1:2 by Job's method and the molar ratio method. The calibration curves were linear up to 4.0 μg/ml of cadmium(II) and 3.0 μg /ml of zinc (II). Sandell's sensitivity was 0.005 μg/cm2 for cadmium(II) and 0.003 p.g/cm2 for zinc(II). The recommended procedure is as follows: To a sample solution containing≤40 μg of cadmium(II) {or <30 μg of zinc(II)}, 0.5 ml of 1.0 × 10-2 M CPC, 0.25 ml of 1.0 × 10-2 M NO-oxine (or CH3-oxine solution), 2.0 ml of a borate buffer (pH 8.2) and 1.0 ml of 1.0 × 10-3 M MTB were added. The mixture was diluted to 10.0 ml with water. After the solution was kept at (2025)°C for 5 min, the absorbance was measured at 630 nm {for cadmium(II)} or at 620 nm {for zinc(II)} against a reagent blank. Nickel(II), cyanide, sulfide and thiocyanate interfered. Aluminum (III) and thorium (IV) could be masked with sodium fluoride, and mercury(II) with 1-ascorbic acid.

Equilibria of iron(III) complexes with xylenol orange and methylthymol blue

A potentiometric and spectrophotometric study of Fe(III) complexes with Xylenol Orange (XO) and Methylthymol Blue (MTB) has been made. The formation constants for the Fe(III) complexes with XO and MTB were determined. Evidence was found for the formations of 1:1 and 2:1 complexes (metal:ligand) and it was assumed that protonated and hydroxo-complexes exist in addition to the simple complex in each case. The hydroxo-complexes are stable over the pH range of 7–12. Suggestions are made concerning the probable structures of these complexes.

Anodic A.C. polarography of methylthymol blue

The anodic a.c. polarographic properties of methylthymol blue (MTB) were investigated in the supporting electrolyte of potassium nitrate containing buffer. The difference in the peak potentials of MTB and EDTA is a good measure of the difference in the stabilities of both chelates. The stability constant of mercury(II)-MTB complex was successfully determined on the basis of that reported for the mercury(II)-EDTA complex.

Anodic a.c. polarography of methylthymol blue

The anodic a.c. polarographic properties of methylthymol blue (MTB) were investigated in the supporting electrolyte of potassium nitrate containing buffer. The difference in the peak potentials of MTB and EDTA is a good measure of the difference in the stabilities of both chelates. The stability constant of mercury(II)-MTB complex was successfully determined on the basis of that reported for the mercury(II)-EDTA complex.

Determination du calcium serique par une technique utilisant le bleu de methylthymol

A simple, specific and rapid colorimetric method for the determination of calcium concentration in serum using methylthymol blue is described. The reagent given can be used both in a manual method and in an automatic method using an auto-analyser without dialysis. The results obtained by the automatic method are compared to those found by the manual method and those obtained by atomic absorption.

Spectrophotometric Determination of Palladium with Methylthymol Blue

AbstractA new, sensitive spectrophotometric method for the determination of palladium(II) with methylthymol blue has been developed. The palladium methylthymol blue complex has an absorption maximum at 530 nm. The colour reaction has a sensitivity of 0.005 µg of palladium/cm2 and obeys Beer's Law over the range 0.4 to 3.24 ppm of palladium. The effects of concentration of perchloric acid, reagent, heating, stability of colour and diverse ions have been investigated. The ratio of metal: ligand in the complex is 1:1 and the formation constant was calculated to be 1.18×104.

Formation constants of alkaline-earth metal complexes with xylenol orange and methylthymol blue

The complexes of the alkaline-earth metals with Xylenol Orange and Methythymol Blue have been studied. Three 1:1 and two 2:1 (metal:ligand) complex species for each indicator and each element have been found to be formed in aqueous solutions, and the formation constants and the arrangements of these complexes have been determined.

Acid equilibria of methylthymol blue and formation constants of cobalt(II), nickel(II), copper(II) and zinc(II) complexes with methylthymol blue

Potentiometric and spectrophotometric studies on acid equilibria and reactions with Co(II), Ni(II), Cu(II) and Zn(II) for Methylthymol Blue (MTB) are described. The equilibrium constants have been calculated. MTB has been found to form 1:1 and 2:1 (mole ratio of metal to ligand) complexes, including protonated ones. The probable configuration of the complexes and the effects on the stabilities have been discussed.

Spectrophotometric study of the chelate of palladium(II) with methylthymol blue

Methylthymol blue reacts very sensitively with palladium(II) to form two complexes. The 1:1 complex has λ max at 530 nm in acidity range 0.02 to 0.05 M with respect to perchloric acid and 1:2 (metal reagent ratio) complex at 500 nm in pH range 6.8 to 7.5. Optimum conditions including the range for adherence to Beer's law, effect of pH, effect of excess reagent and sensitivity are reported for the photometric determination of palladium using methylthymol blue.

Rapid colorimetric determination of calcium in biologic fluids with methylthymol blue.

Gindler, E. Melvin, and King, John D.: Rapid colorimetric determination of calcium in biologic fluids with methylthymol blue. Am. J. Clin. Pathol. 58: 876–382, 1972. A simple and rapid colorimetric method of determining calcium concentration, based on methylthymol blue, is described. Serum proteins and sizable concentrations of phosphate, magnesium, and bilirubin do not interfere significantly. Sensitivity is sufficient to permit ultramicro application, and the color of the calcium-dye complex is completely stable for several hours. The procedure involves no deproteinization, and can be completed within five minutes after serum or plasma have been obtained, and is equally applicable to routine and to “stat” requests. Two simple stock solutions are mixed together in equal volumes to form a working reagent, which, when added to the specimen, gives a blue color with calcium. Absorbance follows Beer’s law at calcium concentrations as high as 12.5 mg. per 100 ml. The results agree closely with those of Gitelman’s o-cresolphthalein complexone (SMA 12/60) procedure, and good accuracy has been shown by recovery data.

Colorimetric determination of thorium with Methylthymol Blue

Thorium forms with Methylthymol Blue (MTB) in alkaline medium (pH 9–10) a complex of the composition Th(MTB) 2, even in the presence of EDTA, which masks almost all metals against the reagent. This can be used for selective determination of traces of thorium (0.5–2.8 ppm) by measurement of the absorbance at 535 nm.

Uranium(VI)‐Methylthymol Blue (penta sodium salt) chelate – A spectrophotometric study

AbstractSpectrophotometric study has been made with a view to investigate the composition and stability of the chelate formed between uranium(VI) and penta sodium salt of Methylthymol Blue (MTB). The composition of the red coloured chelate (λmax510 nm) as established by two different methods, comes out to 1:1 (metal:chelating agent). The chelate is stable between pH 6.2 and 6.9. The average value of log K at 30° (pH 6.7 ± 0.1; μ = 0.1 M) is 5.6 ± 0.2 and ΔG° at the same temperature is −7.7 ± 0.2 kcal/mole.

A determinação do magnésio trocável do solo pelo método espectrofotométrico do metiltimol azul

Êste trabalho apresenta um estudo sobre o método espectrofotométrico do metiltimol azul para a determinação do magnésio trocável dos solos. São apresentados dados relativos à curva de absorção e à estabilidade do composto magnésio-metiltimol azul e do metiltimol azul. No estudo dos interferentes, foram considerados diversos íons, verificando-se que o principal deles é o íon cálcio, o qual é eliminado da solução através da precipitação com solução saturada de oxalato de amônio. Para a extração do magnésio trocável dos solos usou-se uma solução de KC1 1 N.

The spectrophotometric determination of iron(II) with methylthymol blue

Abstract The formation of complexes between iron (II) and methylthymol blue at pH 5.8 and 2.5 was studied. Complexes with the mole ratio 1:2 and 1:1 were found and respective stability constants were determined. A spectrophotometric method for determining iron (II) was devised and reported.

The spectrophotometric determination of uranium(VI) with methylthymol blue

Uranium(VI) and methylthymol blue form a red complex in aqueous solution with maximum development of color at pH values between 6.6 to 6.8 (λ max = 510 mμ). The net molar absorptivity is 10,625 at pH 6.7 and Beer's law is obeyed in the range of 0.4–3.76 ppm of uranium. A procedure is described for the accurate spectrophotometric determination of uranium. The ratio of metal:ligand in the complex is 1:1.